20 year follow up of lingually bonded retainers

ORIGINAL ARTICLE

Twenty-year follow-up of patients withpermanently bonded mandibularcanine-to-canine retainersFrederick A. Booth,a Justin M. Edelman,b and William R. Proffitc

Chapel Hill, NC

Introduction: Many orthodontists believe permanent retention is the only way to maintain ideal toothalignment after treatment. Fixed bonded retainers are now routinely left in place for many years, evendecades. The purpose of this study was to examine the health effects and effectiveness of very long-termretention. Methods: Sixty patients who had had bonded canine-to-canine retainers placed a minimum of 20years previously were recalled. Results: Forty-five still had the retainers still in place, and, of these, only 1had an irregularity index score �2 mm. In this group, the retainers of 28 patients had never broken, and theretainers were repaired once for 8 patients and more than once for 9. The other 15 patients had had theirretainers removed outside the orthodontic practice 5 to 25 years previously. In 13 of these patients, theirregularity index score was �3 mm, and 5 of them had scores �4 mm. Gingival index scores for all teethfrom first molar to first molar in both arches demonstrated no detrimental effects to the mandibular anteriorgingiva from leaving these retainers in place, and the mean score for the maxillary incisor area was better inthe patients with a retained mandibular retainer, suggesting better hygiene in the group with retainers.Conclusion: Long-term retention of mandibular incisor alignment is acceptable to most patients and quite
compatible with periodontal health. (Am J Orthod Dentofacial Orthop 2008;133:70-6)
Throughout the history of our specialty, orth-odontists have sought methods to ensure thestability of corrections achieved during treat-

ment. Mandibular incisor alignment after correction ofcrowding in that area has been a particular problem.

Edward Angle was confident that occlusal forcesagainst teeth in what he described as normal occlusionwould maintain them in that position. This view wasreplaced soon after his death by Tweed’s demonstrationof better stability after premolar-extraction retreatmentof patients with relapse. In spite of considerable criti-cism from his contemporaries, Tweed theorized thatavoiding arch expansion would prevent relapse. Echoesof both views are found in the more recent statement byAndrews1 that “lower teeth need not be retained aftermaturity and extraction of the third molars, except incases where it was not possible to honor the muscula-

From the Department of Orthodontics, School of Dentistry, University of NorthCarolina, Chapel Hill.aAdjunct professor.bResearch assistant.cKenan professor.Reprint requests to: Frederick A. Booth, 222 Fairway Dr, Fayetteville, NC28305; e-mail, [email protected], September 2006; revised and accepted, October 2006.0889-5406/$34.00Copyright © 2008 by the American Association of Orthodontists.
doi:10.1016/j.ajodo.2006.10.023
70

ture during the treatment and those cases in whichabnormal environmental or hereditary factors exist.”

Reitan2 demonstrated that gingival elastic fiberscontribute to relapse after correction of rotations, andEdwards3 described the surgical technique to preventrotational relapse that has become known as circumfer-ential supracrestal fiberotomy. Boese4 combined thistechnique with reproximation of the mandibular ante-rior teeth during and after treatment. He demonstratedgood stability in 40 patients 4 to 9 years after treatmentwho were never retained, but major reductions inincisor width were required.

Other notable concerns related to long-term sta-bility have been the interincisal angle,5 intercaninewidth,5,6 overcorrection of rotations,7 posttreatmentgrowth,8,9 and arch form,10 but, as a result of personalexperience and the classic studies at the University ofWashington by Little et al,10,11 most orthodontistsbelieve that stable treatment is a myth. Studies ofuntreated normal occlusions have shown that archlength decreases and mandibular incisor crowding in-creases throughout life.12,13 The changes that often areaccepted as relapse also occur in untreated persons.

This has led many orthodontists to conclude that theonly way to maintain ideal alignment after treatment issome form of permanent retention,10,14-16 and fixed
bonded retainers now are being left in the mouth for

American Journal of Orthodontics and Dentofacial OrthopedicsVolume 133, Number 1

Booth, Edelman, and Proffit 71

long periods of time. Despite the concern by generaldentists and dental hygienists about the difficulty ofcleaning around these appliances and the risk of devel-oping periodontal problems, there have been relativelyfew studies of their effects on the health of theperiodontium. In periods of up to 3 years, severalinvestigators reported no evidence of hard- or soft-tissue lesions related to a bonded retainer.17-21 Dahl andZachrisson,21 after examining 72 patients with bondedmandibular retainers with retention times of 3 and 6years, found no signs of dental caries or white spots, butwrote that “we must express caution regarding theindiscriminate use of extended retention in routineorthodontics. Little is currently known about how longretainers can or should be used.”

The purpose of this study was to evaluate the healtheffects and the effectiveness of bonded retainers onfollow-up at 20 years or longer.

MATERIAL AND METHODS

From the records of the practice of the senior author(F.A.B.), patients treated with full orthodontic appli-ances and bonded retainers placed between 1977 and1985 were identified. For almost all of that time, the

Table I. Gingival index, anterior region (canine-to-cani

Jaw SurfaceBonding status at

follow-up N

Mandible Facial/buccal Bonded 45Not bonded 15

Lingual Bonded 45Not bonded 15

Maxilla Facial/buccal Bonded 45Not bonded 15


P, Probability that bonded � not bonded, Wilcoxon rank sum test.

Table II. Gingival index, posterior regions

Jaw SurfaceBonding status at

follow-up n

Mandible Facial/buccal Bonded 45Not bonded 15


Maxilla Facial/buccal Bonded 45Not bonded 15


P, Probability that bonded � not bonded, Wilcoxon rank sum test.

bonded retainer was fabricated from .025-in steel wire

and retained with bonding to loops on the canines only.A few patients toward the end of that period had .032-intwisted wire retainers as recommended then by Zach-risson.6 None had the retainer bonded to both theincisors and the canines. Only patients whose pretreat-ment records were available were considered.

An attempt was made to contact patients on this listwho were known to be in the area or could be locatedthrough Internet searching, or whose parents could stillbe contacted at their original address. There was noattempt to select patients who still had retainers in placeor to use any criterion other than those mentionedabove. It was expected that some patients had lost theretainer or had it removed, and this would allowcomparison of those with and without long-term reten-tion. Our goal was to recall at least 60 patients, andefforts were continued until this number was reached:102 contact attempts were made, 72 patients weresuccessfully contacted, and 60 returned for recall ex-amination. For those who were examined, the mediantime since placement of the retainers was 25 years, witha range of 20 to 29 years.

At the recall appointment, a gingival index score forall areas of the mouth (first molar to first molar) was

Gingival index score

Median 75th% Mean SD P value

0.00 0.50 0.28 0.42 .420.33 0.67 0.37 0.420.40 1.00 0.58 0.63 .860.33 1.17 0.66 0.850.00 0.50 0.28 0.39 .290.17 1.00 0.40 0.450.33 0.83 0.50 0.61 .0041.00 1.17 0.93 0.48

Posterior left Posterior right

n SD P value Mean SD P value

9 0.58 .89 0.29 0.48 .663 0.42 0.37 0.601 0.53 .52 0.49 0.63 .663 0.59 0.58 0.703 0.49 .16 0.33 0.56 .060 0.40 0.62 0.600 0.80 .02 0.67 0.82 .037 0.62 1.24 0.93

ne)

25th%

0.000.000.000.000.000.000.000.67

Mea

0.30.30.40.30.30.50.71.2

obtained by using the scoring system of Loe and

American Journal of Orthodontics and Dentofacial OrthopedicsJanuary 2008

72 Booth, Edelman, and Proffit

Silness22 and an adaptation of their method. Scoreswere 0, normal gingiva, absence of inflammation; 1,mild inflammation, slight change of color, slightedema, no bleeding on probing; 2, moderate inflamma-tion, bleeding on probing; and 3, severe inflammation,ulceration, tendency to spontaneous bleeding.

To generate a score, a probe was passed withminimal pressure from 1 interproximal contact throughthe gingival sulcus to the next interproximal contact, onboth the lingual and the facial aspects of each toothfrom first molar to first molar. A separate score wasrecorded for the facial and the lingual aspects of eachtooth, and these scores were averaged to generate ascore for the anterior (canine to canine) and right andleft posterior regions of both arches for each patient.

Facial and intraoral photographs, including close-upphotos of the mandibular anterior region from thelingual and facial aspects to visually record the clinicalappearance of the tissues, were taken. The presence orabsence of the mandibular bonded retainer was noted

Fig 1. The 4 patients with long-term retainerslingual). Patient 1, 26 years posttreatment; payears.

and, if present, whether it had been previously broken

and the number of times repaired. Although the mainpurpose of this study was to evaluate gingival health asrelated to long-term retainer wear, the relative stabilityof the mandibular incisors with and without the long-term retainer was also of interest. Irregularity wascalculated for patients who no longer had a retainer inplace, and for those who still had a retainer but hadmeasurable irregularity, with an adaptation of Little’smethod.23 Occlusal photographs were printed for allpatients, and the width of the teeth in the originalpretreatment dental casts was used to determine theexact enlargement factor for each patient. This varied,but was approximately 2.5 times. With the knownenlargement, the measurements were considered atleast as accurate as direct measurement on dental casts,and certainly adequate to evaluate differences betweenthe retainer and the no-retainer groups.

For evaluation of differences in gingival indexscores between the retainer and the no-retainer groups,the Wilcoxon rank sum test was used. A 1-sample t test

he best gingival index scores (zero, facial and, 22 years; patient 3, 26 years; patient 4, 23

with ttient 2

was used to determine whether the irregularity index



was different from zero for patients who had lost theirretainers. For both tests, the level of significance wasset at 0.05.

RESULTS

Gingival health was assessed with gingival indexscores for the patients with and without retainers asshown in Tables I and II. There was no difference in thescores for the anterior part of the mandibular arch foreither the facial or the lingual sides (Table I). Interest-ingly, there was a statistically significant difference inthe scores for the lingual side of the maxillary arch,with better scores for the patients with a mandibularretainer in place. The same effect can be seen for theposterior areas (Table II).

Photos of patients with the best and worst gingivalindex scores in the mandibular anterior region areshown in Figures 1 through 4, which also illustrate thevariation in long-term irregularity in the patients who

Fig 2. The 4 patients with retainers lost or remand lingual). Patient 1, 24 years posttreatment;years. Note the good alignment in patient 3, wother 3 patients.

had lost their retainer (see below). There were no

enamel lesions on the lingual aspect of the mandibularincisors and canines (white spots, decalcification, car-ies), even in those with poor oral hygiene.

The success of the bonded retainers was alsomeasured. For those who no longer had a retainer, anirregularity score �2 was considered evidence of re-lapse toward crowding. Only 1 of the 45 patients witha retainer still in place had �2 mm of irregularity.Figure 5 shows the patient with the worst relapse and aretainer in place. Of the 15 patients who no longer hadretainers, 13 had irregularity scores �3 mm, and 5 hadscores �4 mm. The scores were significantly differentfrom zero (Table III).

For permanent retention to be a viable option,breakage must be at a level that does not unduly burdeneither the orthodontist or the patient. Table IV showsthe findings in this regard. Of the 45 patients who stillhad a retainer in place 20 years later, 28 (62%) had hadno breakage over that period; 18% required 1 repair;

ith the best gingival index scores (zero, facialt 2, 29 years; patient 3, 21 years; patient 4, 29rying amounts of relapse into crowding in the

oved wpatienith va

and 20% required more than 1 repair.



DISCUSSION

The gingival index data indicate no negative effecton periodontal health from long-term application of abonded mandibular canine-to-canine retainer. Therewas no difference in the patients with and without aretainer in the mandibular anterior region, even thoughcalculus was noted in some patients in both groups(Figs 3 and 4). There was a significant differencebetween the groups in scores for the maxillary arch,with better scores for gingival health in those with amandibular retainer (no patient had a long-term maxil-lary retainer). This probably indicates better daily homecare and more regular recalls for prophylaxis in thepatients who had a retainer. Irregularity of the maxil-lary incisors did not contribute to the poorer gingivalindex scores in the patients who had lost their retainer.There was little maxillary irregularity in any patient,and no difference was noted between the mandibular

Fig 3. The 4 patients with long-term retainersyears posttreatment, gingival index facial 2.0,2.0; patient 3, 20 years, facial 0.33, lingual 2.that patients 2 and 4 show some accumulatiodo not.

retainer and the no-retainer groups. Årtun17 also noted

that a retainer could have a positive effect on hygiene.He commented that “The presence of a retainer wire,with occasional accumulation of plaque and calculus,does not seem to prevent satisfactory hygiene along thegingival margin. In this regard, the patient’s ownattitude and motivation, possibly acquired under theinfluence of the orthodontist, is probably the mainfactor.”

At present, 2 types of bonded 3-3 retainers are inuse: a heavier wire bonded only on the canines and alighter wire (usually multi-stranded) bonded to the inci-sors as well as the canines. Our results apply only to thefirst type of bonded retainer. No long-term data indicatewhether bonding all the teeth makes a difference inperiodontal health, but it seems likely that how well thepatient maintains good hygiene is the major factor.

The facts that nearly 50% of the originally placedretainers were still in place and that two-thirds of those

the worst gingival index scores. Patient 1, 26l 1.83; patient 2, 23 years, facial 0.83, lingualient 4, 25 years, facial 1.0, lingual 1.16. Notetain and calculus, whereas patients 1 and 3

withlingua0; patn of s

retainers had needed no repairs were most encouraging.



All of these were originally bonded before our currentcomposites were available; most received Orthomite

Fig 4. The 4 patients with retainers lost or rem27 years posttreatment, gingival index facial 0.31.6; patient 3, 20 years, facial 1.0, lingual 1.16of these patients experienced some relapsepatient 4.

Fig 5. The patient with a long-term retainer with theworse irregularity score (2.8). Irregularity was so lowthat it was almost unmeasurable in 43 of the 45 patientswho still had a retainer.

(Rocky Mountain Orthodontics, Denver, Colo), an

acrylic liquid/powder mix applied to the teeth with abrush. A recent report shows almost no breakage witha more modern bonding technique.24

These findings have caused the senior author(F.A.B.) to return to his original technique using.025-in wire with loops at the canines for the bondedretainer. This is after many years of using the innova-tions of Zachrisson6 of the spiral .032-in wire and thenan .032-in straight wire microetched at the attachmentsto the canines. It may be that the smaller diameter wirecan flex slightly and accept some shock without break-ing, and the smaller wire diameter might also reducethe occlusal load during mastication.

CONCLUSIONS

The data from this sample of 60 patients, 45 ofwhom had bonded 3-3 retainers in place for 20 to 29years, indicate that orthodontists can be confident in

ith the worst gingival index scores. Patient 1,ual 3.0; patient 2, 22 years, facial 1.0, lingual

ent 4, 28 years, facial 0.0, lingual 1.16. Threerd crowding, and space opened slightly in

oved w3, ling; patitowa

recommending permanent retention to maintain the

st.



alignment of the mandibular anterior teeth. It clearly ispossible to maintain good hygiene and periodontalhealth with a bonded retainer in place. With goodtechnique, breakage is not a major problem and shouldnot be used as a reason not to place bonded retainers.

We thank Ceib Phillips for statistical consultation,Debora Price for the statistical analysis, and RenelleHuss and Dr Booth’s staff for their help in contactingpatients and collecting data.

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Table III. Irregularity index, patients with lost retainers

n Lower quartile Median Upper quar

15 2.06 mm 3.28 mm 4.22 mm

P, Probability that irregularity index differs from zero, 1-sample t te

Table IV. Breakage and repair with long-term lingualretainers

TotalNeverbroken

Repairedonce

Repairedtwice

Repaired3 times

Repaired4 times

45 28 8 2 6 1

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24. Rogers MB, Andrews LJ II. Dependable technique for bonding a3 � 3 retainer. Am J Orthodod Dentofacial Orthop 2004;126:

Mean SD t value P value

3.30 mm 1.55 mm 8.24 �.0001

tile

231-3.

20 year follow up of lingually bonded retainers

Health & Medicine

treatment of patients

bonded mandibular canine

canine retainers frederick

bonded canine

fixed bonded retainers

gingival index scores

irregularity index score

retained mandibular